The invention relates to a self-locking speed wrench with a fixed clamping jaw, which is rigidly attached to a handle and a pivoting movable jaw attached to the same handle.
These types of speed wrenches, depending on their jaw configuration, may be used as a bolt wrench, pipe wrench or a combination thereof. They have the advantage over rigid or adjustable wrenches or pliers in that the speed wrench adjust itself to any diameter and wrench size and that the necessary tension force is applied by movement of the handle in the tightening direction. Such wrenches may be used as ratchet-type wrenches since tension is released when the handle is moved in the opposite direction.
In a known self-locking speed wrench (U.S. Pat. No. 4,651,597, FIG. 4), the movable jaw is forced into a position by a leaf spring located inside the handle. This ensures self-locking action of the movable jaw as soon as the handle is moved in the tightening direction.
It is difficult and almost impossible to remove the speed wrench from the work piece by one hand only, especially in wrenches with notched jaws and the ones that have a ratchet-like action of 15.degree. steps, since the self-locking wrench is held in place by its notches and the locking action is even increased more when trying to remove it. Therefore, the known speed wrench has an actuating lever attached to the movable jaw that points in the direction of the handle. By applying pressure on this actuating lever, the movable jaw is moved against the direction of tension and against the force of the leaf spring and is thereby turned to the open position, which makes removal of the speed wrench possible.
Handling of this actuating lever is however complicated mainly in situations where space is limited. Therefore, another known speed wrench (U.S. Pat. No. 4,651,597, FIG. 11) has a sliding actuating lever located on the side of the handle to actuate the movable jaw whereby the actuating lever is attached to a push rod that moves the movable jaw. However this actuating sliding lever is not used only to open the movable jaw but also to lock it. This wrench does not have a leaf spring that forces the clamping jaw into the closed position. Hereby the handle has longitudinal aligned slots along the entire length of the handle, which weakens the handle and also results in a complicated construction of the speed wrench.
A manual mechanism is used to open the wrench in a known self-locking speed wrench that is designed as a pipe wrench (DE 138 692). This mechanism has a push rod that actuates the movable jaw and a switching lever on the handle moves this push rod against the force of a bolt pressure spring.
A leaf spring pushes on one side of the movable jaw of a bolt wrench with parallel sliding jaws (U.S. Pat. No. 1,501,329). A movable actuating slide button along the handle actuates a two-pronged lever, which pushes in opposite direction on the movable jaw.
A leaf spring assists in the turning movement of a manual lever in the handle and in the movement of the sliding jaw, but not on the pivoting jaw in a known speed wrench with parallel sliding jaws (DE 12 99 370).